Every tarpaulin we sell has a GSM rating – grams per square metre – and it is the single most important number when choosing a tarp. Pick too light and the sheet shreds in the first storm; pick too heavy and you pay for strength you do not need and wrestle with a sheet twice the weight. Here is how to get it right first time.
What does GSM mean on a tarpaulin?
GSM measures the fabric's density: a 2m x 3m tarp at 100gsm weighs about 0.6kg, while the same sheet at 500gsm weighs 3kg. Higher GSM means thicker weave, thicker waterproof coating, better tear strength and longer UV life – but also more weight and cost.
Tarpaulin weight guide
- 80–120gsm (economy/light duty): short-term DIY cover, dust sheets, temporary garden protection. Expect one season of use.
- 140–200gsm (medium duty): garden furniture, firewood, camping groundsheets, market stalls. A good all-rounder – see our medium duty tarpaulins.
- 250–350gsm (heavy duty): construction sites, roofing repairs, trailers, machinery and farm use. Handles UK winters year-round – browse heavy duty tarpaulins.
- 500gsm+ (super heavy duty/industrial): long-term outdoor exposure, haystacks, lorry covers, scaffolding sheets. Built to live outside for years – see super heavy duty tarpaulins.
Material matters too
At the same GSM, PVC-coated tarps outlast plain polyethylene (PE) for abrasion and UV, while canvas tarpaulins trade a little waterproofing for breathability – the right choice for classic cars and machinery that must not sweat underneath the cover.
Quick answer
For most outdoor jobs in the UK, 250gsm is the sweet spot: fully waterproof, UV-stable and tough enough for building sites, but still manageable by one person. If the cover will stay outside for more than a year, go 500gsm or higher.
Still unsure? Contact our team – we manufacture bespoke sheets and can advise on the right weight for your exact application.